1. Field of the Invention
This invention relates to an improved system and method for providing 20% ethanol solutions meeting bioburden and endotoxin specifications useful for storing, reusing, and/or rejuvenating Protein A used in monoclonal antibody production.
2. Brief Description of the Related Art
Pharmaceutical and biotechnology companies produce monoclonal antibodies to manufacture cancer-specific drug products. The antibody products are purified by filtering them through substrate/media which is coated with Protein A, a product which is a cell wall constituent having binding affinity to the Fc portion of certain immunoglobulins. Protein A is instrumental in protecting against certain tumors, carcinogens, toxins, as well as certain fugal matter and parasites. Protein A is both important and expensive. However, through “cleaning”, it can be reused and/or rejuvinated by cleaning and storing it in a 20% ethanol solution. Protein A therefore may remain stored between manufacturing runs where it may be needed. The 20% ethanol solution must meet certain requirements for satisfying bioburden and endotoxin levels. Bioburden is generally considered to be the population of viable microorganisms on a product or package. Endotoxin is sometimes also referred to as lipopolysaccharides which are present in cell membranes of Gram-negative bacteria (e.g., E. coli). Many DNA applications are endotoxin sensitive, and as a result endotoxins may reduce the transfection efficiency of endotoxin-sensitive cell lines.
The 20% ethanol solution required for use in connection with Protein A storage/rejuvination is prepared by using high quality water to dilute pure ethanol to a 20% solution, and then filtering the solution through a filter, such as a 0.22 micron filter, into a clean or sterile container. Using a 0.22 micron filter is a common practice to sterilize liquid solutions. Bioprocess containers, such as, for example, flexible plastic bags, are also utilized, such as for example, with intravenous solutions, which may also utilize tubing and an in-line filter.
There are drawbacks with the current ways in which 20% ethanol is obtained and utilized for the demands of those requiring a sterile solution meeting the specification for bioburden and endotoxin. Because of the specifications which may relate to sterility, ethanol is used, and regulations require 20% ethanol, and filtration requirements as well, such as, for example filtering though a 22 micron filter. In addition, testing for endotoxin is frequently done to ensure sterility, or that a product conforms to a particular sterility standard. Ethanol solutions may be used, and generally, they must conform to sterility requirements. Generally, ethanol is sold as pure ethanol. Companies who have a requirement for 20% ethanol, therefore, must purchase pure ethanol, and then from that make a 20% ethanol solution. When the 20% ethanol solution is used for a process which must meet bioburden and endotoxin specifications, the companies in addition to mixing pure ethanol with purified water to achieve the 20% solution, must then filter the solution, such as through a 0.22 um filter into a clean or sterile container. Storing the 100% ethanol on site and preparing the 20% ethanol solutions from the stored 100% ethanol when they are needed waste time, money and manufacturing resources of companies requiring 20% ethanol solution, since special equipment is required to store pure ethanol which is not needed to store 20% ethanol solutions, since manufacturing resources must be allocated to handling the pure ethanol and the production of 20% ethanol solutions which might otherwise be allocated to maximize finished drug production, for example, and since production might be slowed down awaiting production of the 20% ethanol solution. Further, a mistake made during the on site production of 20% ethanol solution may result in the solution not being usable, therefore wasting resources and shutting down production of a finished drug product whose production is dependant upon the 20% ethanol solution while a new batch of 20% ethanol solution is prepared to replace the unusable batch to which the mistake was made. Further, an unusable batch of ethanol solution, if mistakenly used in the production of a finished drug product, for example, may adversely affect bioburden and endotoxin levels, resulting non-conformity of materials used in the production of the finished drug product and/or the finished drug product itself. Also, steps must be taken to safely ship and store pure (100%) ethanol, since pure ethanol is considered flammable and must be handled and stored in a manner that meets federal, state and local guidelines for hazardous, flammable material.
A need exists for a system for providing a 20% ethanol solution which may be provided in a form which is directly usable and which still meets requirements for bioburden and endotoxin specifications. A system which is able to provide an end user with a 20% ethanol solution which meets the bioburden and endotoxin specifications, and can therefore be directly used by the end user without requiring the end user to dilute pure ethanol to a 20% ethanol solution, saves time and resources for the end user, and is safer to transport to the end user than pure ethanol.